Dial-up, ISDN (integrated services digital network) and DSL (digital subscriber line) services provide for Internet access by transmitting data over existing twisted pair telephone lines to a central office of the telecommunications loop provider where the subscribers physically connect to a network access provider (NAP) and send and receive data communications to the Internet via a network access server (NAS) using, for example, point-to-point protocol. In order to use the Internet, the user typically must obtain an IP address from a local pool at the Point of Presence (POP) maintained by the NAP that the user connects to, or the user must obtain an IP address from a home gateway server (HGS) at an Internet service provider (ISP). Often, the ISP and the NAP are separate entities, both physically and organizationally.
When the ISP and NAP are separate, there is a need to provide the subscriber, or user, with an IP address from the HGS via the NAS. Two methods are currently used.
One existing method involves manual planning of the IP address allocation between the NAP and the ISP. In this method, the ISP gives a block of IP addresses to the NAP, and the NAP configures the NAS with the block of IP addresses so that the NAS may give them out. The addresses are available to the user directly from the NAS. However, both the NAP and the ISP must agree to share the same routing protocols, which may be undesirable. The approach is also administratively complex and time consuming because any change in IP address allocation will result in a need to reconfigure all the network access servers involved and many network access servers may need to be reconfigured.
A second existing method involves tunneling IP address requests from the NAS to the home gateway server (HGS) of the ISP. This avoids route-sharing and administrative complexity. However, the tunneling method is not truly scalable because the HGS must maintain information for each individual tunnel that may be established. Currently, there is no HGS that can scale up to expected demand.
Because of the limitations of the existing methods, there is a need for providing an IP address from an ISP to a user via a NAS in a dynamic and scalable manner.